"Cop-a-Squat" originally meant taking either a piss or a shit in a non-regular or non-familiar/public setting. "Pop-a-squat" has evolved from that general intent, now meaning taking/finding a semi-permanent seat in a public setting that even if not designed to accomodate asses (like a toilet in a public restroom), still for a short period of time provides butt rest. Although introduced in the US in the late '90's, and heavily promoted in New York City, "private, 'public' time-controlled spaces", like the self-cleaning, time-controlled public 'porto-potties' just didn't mesh with true western socio-public values.

So, cop-a-squat used to mean finding a public place to "eliminate", even if it wasn't technically a restroom, and includes friends bathrooms. The definition "pop a squat" s/b subcategorized with "cop a squat" because both actions involve claiming a temporary place for ones' Ass. I submit the merging of the definitions/terms, and the definition be:
Cop a squat-
any temporary placement of the gluteal physio-segment, whether clothed or not, that provides physio-relief, whether through the process of elimination or the temporary relief of musculo-skeletal distress (needing to sit your broken-ass body down for 20 minutes).